<!DOCTYPE html>
<html>
<!-- Created by GNU Texinfo 7.1, https://www.gnu.org/software/texinfo/ -->
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<!-- Copyright © 1987-2023 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation.  A copy of
the license is included in the
section entitled "GNU Free Documentation License".

This manual contains no Invariant Sections.  The Front-Cover Texts are
(a) (see below), and the Back-Cover Texts are (b) (see below).

(a) The FSF's Front-Cover Text is:

A GNU Manual

(b) The FSF's Back-Cover Text is:

You have freedom to copy and modify this GNU Manual, like GNU
     software.  Copies published by the Free Software Foundation raise
     funds for GNU development. -->
<title>__has_c_attribute (The C Preprocessor)</title>

<meta name="description" content="__has_c_attribute (The C Preprocessor)">
<meta name="keywords" content="__has_c_attribute (The C Preprocessor)">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<meta name="viewport" content="width=device-width,initial-scale=1">

<link href="index.html" rel="start" title="Top">
<link href="Index-of-Directives.html" rel="index" title="Index of Directives">
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
<link href="Conditional-Syntax.html" rel="up" title="Conditional Syntax">
<link href="_005f_005fhas_005fbuiltin.html" rel="next" title="__has_builtin">
<link href="_005f_005fhas_005fcpp_005fattribute.html" rel="prev" title="__has_cpp_attribute">
<style type="text/css">
<!--
a.copiable-link {visibility: hidden; text-decoration: none; line-height: 0em}
span:hover a.copiable-link {visibility: visible}
-->
</style>


</head>

<body lang="en">
<div class="subsection-level-extent" id="g_t_005f_005fhas_005fc_005fattribute">
<div class="nav-panel">
<p>
Next: <a href="_005f_005fhas_005fbuiltin.html" accesskey="n" rel="next"><code class="code">__has_builtin</code></a>, Previous: <a href="_005f_005fhas_005fcpp_005fattribute.html" accesskey="p" rel="prev"><code class="code">__has_cpp_attribute</code></a>, Up: <a href="Conditional-Syntax.html" accesskey="u" rel="up">Conditional Syntax</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index-of-Directives.html" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<h4 class="subsection" id="g_t_005f_005fhas_005fc_005fattribute-1"><span>4.2.8 <code class="code">__has_c_attribute</code><a class="copiable-link" href="#g_t_005f_005fhas_005fc_005fattribute-1"> &para;</a></span></h4>
<a class="index-entry-id" id="index-_005f_005fhas_005fc_005fattribute"></a>

<p>The special operator <code class="code">__has_c_attribute (<var class="var">operand</var>)</code> may be
used in &lsquo;<samp class="samp">#if</samp>&rsquo; and &lsquo;<samp class="samp">#elif</samp>&rsquo; expressions in C code to test
whether the attribute referenced by its <var class="var">operand</var> is recognized by
GCC in attributes using the &lsquo;<samp class="samp">[[]]</samp>&rsquo; syntax.  GNU attributes must
be specified with the scope &lsquo;<samp class="samp">gnu</samp>&rsquo; or &lsquo;<samp class="samp">__gnu__</samp>&rsquo; with
<code class="code">__has_c_attribute</code>.  When <var class="var">operand</var> designates a supported
standard attribute it evaluates to an integer constant of the form
<code class="code">YYYYMM</code> indicating the year and month when the attribute was
first introduced into the C standard, or when the syntax of operands
to the attribute was extended in the C standard.
</p>
</div>



</body>
</html>
